This invention relates to a novel Ziegler type supported catalytic component for .alpha.-olefin polymerization which is of highly uniform particle diameter, of good fluidity and has a high degree of polymerizing activity and high stereospecific polymer productivity (hereinafter will be called the catalytic component for short unless other wise specified) and to a method of carrying out homo- or co-polymerization (hereinafter will be called (co-)polymerization) of an .alpha.-olefin in the presence of a catalyst composition consisting of the above stated catalytic component and an organo-aluminum compound.
More particularly, the invention relates to a catalytic component for .alpha.-olefin polymerization prepared through steps in which (a) a solid product obtained by allowing an organo-magnesium compound expressed by a generic formula of R'MgX' (wherein R' represents a hydrocarbon group having 1 to 20 carbon atoms and X' either a halogen atom chosen out of chlorine, bromine and iodine or a hydrocarbon group having 1 to 20 carbon atoms) to react with carbon tetrahalide in the presence of an electron donor compound is subjected to a solid-liquid separation process; (b) the separated solid product is heat treated with a carbon halide; (c) the heat treated solid product is treated with phenols at 90.degree. to 180.degree. C. or may be subjected to heating treatment under reduced pressure after this treatment with phenols; and (d) the phenol treated product is treated further with a halogenated titanium compound. The invention also relates to a method for (co-)polymerization of an .alpha.-olefin which is carried out either in the presence of a catalyst composition consisting of the catalytic component thus obtained and an organo-aluminum compound or with use of a concomitant electron donor compound together with the catalyst composition.
An important feature of the present invention resides in that the polymer product obtainable in accordance with the invention is great in weight per unit weight of the catalytic component, that is, the catalytic component has a high degree of polymerizing activity. Another important feature resides in that the insufficient bulk density and the insufficient stereospecific polymer productivity which have been the shortcomings of the conventional supported catalytic components of the Ziegler type can be substantially improved. In addition to these important features, it is a further important feature of the invention that stereospecific polymerization of an .alpha.-olefin, such as propylene in particular, at a high temperature which has hitherto been extremely difficult is now rendered feasible by the present invention.
Generally, the catalysts which have been used for the manufacture of stereospecific .alpha.-olefin polymers are of the type known by the name of a Ziegler-Natta catalyst consisting of a transition metal belonging to the groups IV-VI of the periodic table and an organo-metallic compound of a metal belonging to the groups I-III of the periodic table.
Catalytic components that have been employed in the industrial manufacture of .alpha.-olefin polymers such as propylene, butene-1, etc. are catalytic components having titanium trichloride as main constituent, such as an .alpha.-olefin polymerizing catalytic component prepared by activating, through a pulverizing process or the like, an eutectic mixture consisting of aluminum chloride and titanium trichloride obtained by reducing titanium tetrachloride with metal aluminum as the compound of the transition metal belonging to the groups IV-VI of the periodic table; and an .alpha.-olefin polymerizing catalytic component prepared through a process in which titanium trichloride obtained by reducing titanium tetrachloride with an organo-aluminum compound is activated through treatment carried out with an organo-ether compound and titanium tetrachloride. Generally, these catalytic components are used in combination with an organo-aluminum compound in a catalytic composition for polymerization of an .alpha.-olefin.
However, the .alpha.-olefin polymer obtained by carrying out polymerization in the presence of such a catalytic composition contains several hundred ppm of residue of the catalyst therein. In such catalytic residue, the transition metal such as titanium accelerates the deterioration of the polymer. Therefore, it is necessary to remove such catalytic residue as much as possible. In an .alpha.-olefin manufacturing plant, at present, the catalytic residue is, therefore, being removed by washing the polymer product with alcohols.
To lower the cost of manufacture of an .alpha.-olefin polymer, there have recently been proposed many catalytic components prepared to enhance their polymerizing activity to such a high degree that permits omission of a deashing step otherwise required for washing and removing a transition metal such as titanium from the polymer product during an .alpha.-olefin polymerization process. In deed, if it is possible to have the polymer produced to an amount of about one hundred thousand to several hundred thousand parts by weight per unit weight of the transition metal such as titanium, the amount of the residual transition metal such as titanium remaining in the polymer product could be held at several ppm or less. Then, the acceleration of deterioration of the polymer product due to the transition metal would become negligible to permit omission of the deashing step, so that the cost of manufacture of the .alpha.-olefin can be reduced as desired.
Most of these catalytic components of the prior art are of the Ziegler type and have been prepared in such a manner that a magnesium chloride, either with its surface treated by some method or without any surface treatment, is used as carrier to have titanium tetrachloride supported by the surface thereof. The catalytic component manufacturing methods of the prior art using magnesium chloride as start material and as carrier, however, necessitate a pulverizing process for pulverizing and activating the magnesium chloride. The powdery magnesium chloride obtained through the pulverizing process is in a crashed state which not only lacks homogeneity in particle diameter but also includes a great amount of fine powder. Therefore, both the catalytic component thus obtained from the use of such magnesium chloride and the polymer obtained from the catalytic component have been very poor in morphology such as fluidity.
Meanwhile, there also have recently been proposed many catalytic components of improved particle properties which are obtained by using an organo-magnesium compound as start material in the preparation of a carrier. Typical examples of methods for obtaining such catalytic components include a method disclosed by Japanese Patent Applicaton Laid-Open No. 54-123594 in which a complex consisting of an organo-magnesium compound and an organo-aluminum compound is allowed to react with a tertiary alkyl halide and then a product thus obtained is treated with carboxylic acid ester and titanium tetrachloride; a method disclosed by Japanese Patent Application Laid-Open No. 54-133584 in which a solid product obtained through a reaction between an organo-magnesium compound and an organic halide is treated with an electron donor compound and then is arranged to support titanium tetrachloride; a method disclosed by Japanese Patent Application Laid-Open No. 54-76492 in which a reaction product obtained from a reaction between an organo-magnesium compound and a polyhydric alcohol is treated with an electron donor compound and then is arranged to support a titanium tetrachloride; methods disclosed by Japanese Patent Application Laid-Open No. 53-43094 and Japanese Patent Application Laid-Open No. 54-107987 in which a carrier obtained by allowing a silicon tetrachloride to react with a reaction product obtained from a reaction between an organo-magnesium compound and a hydropolysiloxane or a carrier obtained by allowing silicon tetrachloride to react directly with an organo-magnesium compound is processed to support titanium tetra-chloride; a method disclosed by Japanese Patent Application Laid-Open No. 55-58207 in which a solid product obtained through a reaction between an organo-magnesium compound and silicon tetrachloride is treated with an alcohol and carboxylic acid ester and then is treated further with titanium tetrachloride; and a method disclosed by Japanese Patent Application Laid-Open No. 55-133408 in which a solid organo-magnesium compound is treated with an aromatic alcohol and an electron donor compound and then is treated further with titanium tetrachloride.
However, catalytic components obtained in accordance with these prior art methods either do not have a sufficiently high degree of polymerizing activity or, even if they have a high degree of polymerizing activity, have a low degree of stereospecific polymer productivity or have such other shortcomings that: Their polymerizing activity is high at the initial stage of polymerization but comes to quickly lower thereafter or gives a polymer product of low bulk density. These shortcomings seem to have been preventing them from becoming acceptable for practical applications.
Another shortcoming of the prior art catalytic supported components of the Ziegler type resides in their polymerizing properties at high temperature. The higher the polymerizing activity of the catalytic component is, the greater the momentary chlorific value will be. Therefore, even if the temperature control over the whole inside of a reactor is possible, it is nearly impossible to prevent local over-heating. A catalytic component of high polymerizing activity is therefore required to be capable of retaining its performance even when an .alpha.-olefin polymerizing process is carried out at high temperature.
Meanwhile, for simplification of an .alpha.-olefin polymerizing process, studies for polymerization of an .alpha.-olefin in a gas phase have recently been actively conducted. The gas phase polymerization process is to be carried out at a high temperature for polymerization of an .alpha.-olefin. Gas phase polymerization of propylene, for example, is generally carried out at a high degree of temperature exceeding 90.degree. C. With the prior art catalytic components, however, the polymerization temperature is generally 60.degree. to 70.degree. C. or 80.degree. C. at the most. Polymerization at temperature exceeding 80.degree. C. with the prior art catalytic components results in a conspicuous decrease in the productivity for a stereospecific polymer. The catalytic components of the prior art are thus not usable for polymerization of propylene at high temperature. In the case of a gas phase polymerization apparatus using a fluidized bed, the particle diameter of the catalytic component must be highly uniform. Whereas, a catalytic component obtained through a pulverization process is not uniform in particle diameter and contains a great amount of fine powder of the catalytic component. Therefore, such a catalytic component is hardly usable for the polymerization process. In view of this, it has been desired to have a catalytic component that has highly uniform particle diameter as well as a polymerizing property suitable for high temperature in the field of gas-phase polymerization of an .alpha.-olefin.
The present inventors strenuously conducted studies for elimination of the above stated shortcomings of the catalytic components of the Ziegler type of the prior art having titanium supported by a carrier. These studies have resulted in the completion of the present invention.